Method of treating fibrous cellulosic materials to impart flame resistance thereto, compositions therefor, and products thereof



Patented Aug. 22, 1950 METHOD or TREATING muons omn- LOSIC mrnams 'roman-r FLAME RESISTANCE THERETO, COMPOSITIONS THEREFOR, AND PRODUCTSTHEREOF Anne MacMillan Loukomaky, North Plainfield,

Roy H. Kienle, Bound Brook, and Theodore F. Cooke, Martinsville, N. Jassignors to American Cyanamid Company, New York, N. Y., a corporationof Maine No Drawing. Application February 15, 1949, Serial No. 76,644

This invention relates to a method of impart- 17 Claims. (01. 117-137)ing flame resistance to a cellulosic material, more v particularlyacellulosic material of the class consisting of natural and regeneratedcelluloses and mixtures thereof, and specifically to a textilecomprising fibers of such cellulosic materials, as well ascompositionsused in such treatments and to the flame-resistant cellulosic productsthereof.

Various compounds and compositions have been used or suggested for useas agents for treating fibrous cellulosic and other normally flammableorganic materials in order to render them resistant to flame. suchcompounds and compositions see the book entitled "Flameproofing TextileFabrics, edited by Robert W. Little and published in 1947 by ReinholdPublishing Corporation, New York, N. Y., and the references citedtherein. Reference also is made to the copending application of one ofuse (formerly Anne MacMillan, now Anne MacMillan Loukomsky) Serial No.691,866, filed August 20, .1946, now abandoned, wherein is disclosed andclaimed a method of imparting flame resistance to cellulosic textileswhich comprises impregnating such textiles with a phosphate of anacyclic amidine, specifically monoguanidine phosphate, and a member ofthe group consisting of urea, biuret, ammonium cyanate, cyanamide anddicyandiamide in amounts sufllcient to impart flame resistance theretoupon subsequent heating, and then heating the impregnated textiles at atemperature of at least 135 C. to form a washfast, flame-resistantfinish therein and thereon.

Agents or treatments for imparting flame resistance to normallyflammable organic materials properly may be classified as (1) temporary,(2) semi-durable and (3) permanent or durable, based on their durabilityin providing continued resistance of the treated textile or othermaterial to flame during use. See page 6 of the aforementioned book byLittle for a more complete description of these classes. The presentinvention is concerned primarily with certain new and usefulimprovements in the permanent or durable agents or treatments of thekind aforementioned.

The durable treatments heretofore used or suggested have been of threegeneral kinds or types:

1. Urea-phosphate type. 2. Double-bath precipitation type. 3. Metallicoxide-chlorinated body type.

See Littles book, supra, pages 179-284, for a complete description anddiscussion of each of these types. One of the main objections to the Fora description of urea-phosphate type of treatment is the tenderingeffect of the treatment on the cellulosic material whereby its tensilestrength is reduced considerably. The double-bath precipitation and themetallic oxide-chlorinated body types of treatments generally yieldcellulosic textiles having a harsh or stiff hand, so that the treatedtextile has a limited field of utility.

The present invention is based on our discovery that fibrous cellulosicmaterials including those composed solely or comprised mainly (that is,preponderantly by weight) of fibers of natural cellulose (that is,cellulosic materials of natural origin), regenerated cellulose (moreparticularly viscose rayons) and mixtures thereof can be renderedsubstantiall permanently resistant to flame by suitably treating themwith compositions of the kind hereinafter described. Our treated fibrouscellulosic textiles in thread, yarn, fabric or other form are unique inthat they are characterized not only by their substantially permanentflame resistance but also by their improved hand or feeling to the touchas compared with the hand of textiles that have been given a double-bathprecipitation or a metallic oxidechlorinated body type of treatment,thereby increasing the field of utility of flame-resistant textiles.Furthermore, these properties are obtained without excessive tenderingof the textile, .the'

treated textile in general having a tensile strength (average of the sumof the tensile strength of the warp and filling) of at least of that ofthe untreated textile when similarly tested for tensile strength, and inmany cases a tensile strength which is even higher than that of theuntreated textile.

More particularly we have discovered that flame-resistant, fibrous,cellulosic textile materials comprising or composed of fibers of naturalcellulose, regenerated cellulose or a mixture thereof and which have agood hand, that is, a.

hand or feeling to the touch which meets the requirements of the trade,and good tensile strength characteristics are produced by impreghatinthe normally flammable cellulosic textile with certain materials inparticular proportions or ranges of proportions which are critical incarrying the invention into effect. A substantial proportion of theimpregnant initially applied is fixedly held by the cellulosic textileafter subsequent heat treatment and washing; hence the flame-resistanttextiles of our invention properly may be designated as being of thedurable type or kind.

When the flame-resistant cellulosic textiles of our invention are testedfor flame resistance using a vertical flame test, such as is describedhereinafter, the char length" (charred length) ordinarily is not morethan about 6 inches, e. g., from 3 to inches, when the textile material(e. g., cotton cloth or viscose rayon fabric) which has been treated andthen subjected to 5 Washes in neutral soap solution is one weighing 4ounces or more per square yard, and not more than about 8 inches, e. g.,from 3 to 7 /2 inches, when the fabric which has been treated weighssubstantially less than 4 ounces, e. g., 2 or 3 ounces per square yard.

In practicing our invention a cellulosic material, more particularly afibrous cellulosic material of the kind defined in the first paragraphof this specification, is impregnated with ingredients comprising (1) afinely divided oxide of antimony, specifically antimony trioxide, and(2) a thermally unstable, halogen-containing thermoplastic substance,more particularly a thermoplastic substance containing at least byweight of combined halogen and capable of rupturing under heat atcarbon-halogen bonds, the ingredients of (1) and (2),.which together aredesignated hereinafter as (A), being employed in a weight ratio of 1part of the former to from 0.6 to 20 parts, more particularly from 0.8to 4 parts, of the latter. Examples of the thermoplastic substances of(2) that may be employed, alone or in the form of mixtures thereof, arehalogencontainlng vinyl resins in which not less than 20% by weight ofcombined halogen is present, for instance, polyvinyl halides (e. g.,polyvinyl chloride, polyvinyl bromide, etc.), polyvinylidene halides (e.g., polyvinylidene chloride, polyvinylidene bromide, etc.) copolymers ofa vinyl halide and a vinylidene halide (e. g., a copolymer of vinylchloride and vinylidene chloride), copolymers of a vinyl halide and anacrylic ester (for instance, a copolymer of vinyl chloride and an alkylacrylate (e. g., methyl, ethyl, propyl, butyl, etc, acrylates),halogenated (e. g., chlorinated) paraiilns containing not less than 20%by weight of combined halogen, more particularly from about or up to orby weight of combined chlorine, bromine, or other halogen, etc. Inaddition to the ingredients of (1) and (2), other ingredients with whichthe cellulosic material is impregnated are (3) a water-soluble salt (ormixtures thereof) of an oxygen-containing acid of phosphorus wherein thephosphorus atom has a valence of 5, e. g., a guanidine phosphate, adiguanidine pyrophosphate, diammonium hydrogen phosphate, sodiumpolyphosphate, ammonium metaphosphate, the mono-, diand trialkylaminepyrophosphates, etc., and (4) a water-soluble nitrogenous substance ofthe group consisting of cyanamide, dicyandiamide and mixtures thereof.The ingredients of (3) and (4), which together are designatedhereinafter as (B) are employed in a weight ratio of 1 part of theformer calculated as phosphoric acid (HJPOO to from 0.2 to 5.5 parts,more particularly from 0.3 to 4.5 parts and preferably from 0.5 to 2parts of the latter, while the ingredients of (A) and (B) are employedin a weight ratio of 1 part of the former to from 0.2 to 8 parts, moreparticularly from 1 to 3 parts, of the latter, The present inventiondiffers from the invention disclosed and claimed in our copendingapplication Serial No. 64,416, filed December 9, 1948, in that in theinvention of the earlier filed application the finely divided metallicoxide is selected from the group consisting of tin, titanium, antimonyand bismuth oxides and mixtures thereof, whereas in the presentinvention it is an oxide of antimony, specifically antimony trioxide;and the water-soluble nitrogenous substance in the earlier case isselected from the group consisting of urea, biuret, ammonium cyanate,ammonium dicyanimide and mixtures thereof, while in the present case itis selected from the group consisting of cyanamide, dicyandiamide, andmixtures thereof. Furthermore, in the invention of our earlier filedapplication the water-soluble nitrogenous substance is employed in aweight ratio of from 1 to 20 parts thereof for each part, calculated asHaPO4, of the oxygencontaining acid of phosphorus, whereas in thepresent invention the water-soluble nitrogenous substance is used in aweight ratio of from 0.2 to 5.5 parts thereof for each part, calculatedas HaPO4, of the oxygen-containing acid of phosphotos.

The fibrous cellulosic material may be impregnated with thaforementioned ingredients in one or more steps or stages. Thus, it maybe impregnated with a dispersion, more particularly an aqueousdispersion, containing the ingredients mentioned in the precedingparagraph within the ranges of proportions therein specified. Thetreated cellulosic material is dried at a suitable temperature, e. g.,at 40 or 50 to or C., and then heated at a higher temperature within therange of C. (about 135 C.) to 200 C. (about 200 0.). During this latterheat treatment a complex reaction takes place with the result that thefinished cellulosic textile in thread, yarn, fabric, felted or otherform is rendered substantially permanently resistant to flame, that isto say, the finished textile is resistant to flame even after numerouslaundering or dry-cleaning operations. After the heat treatment, theimpregnated cellulosic material is washed, e. g., with water, to removewater-soluble substances which are usually present therein.

Alternatively, the fibrous cellulosic material may be impregnated firstwith an aqueous solution containing a guanidine phosphate or otherwater-soluble salt of an oxygen-containing acid of phosphorus whereinthe phosphorus atom has a valence of 5 (or a mixture of such salts) andcyanamide, dicyandiamide or a mixture thereof. The water-soluble salt ofthe acid of phosphorus and the water-soluble nitrogenous substance(cyanamide, dicyandiamide or a mixture thereof), which together aredesignated herein as (B), are employed in ratios by weight within theranges mentioned hereinbefore. The impregnated fibrous material isdried, heated and washed as described in the preceding paragraph withreference to the one-step process. Thereafter it is treated, as byimmersion in a bath containing the same, with a liquid dispersion, moreparticularly an aqueous liquid dispersion, containing a finely dividedoxide of antimony, more particularly finely divided antimony, trioxide,and, also, a thermally unstable, thermoplastic substance containing atleast 20%. pr ferably at least 40%, of combined chlorine or otherhalogen and which is capable of rupturing under heat at carbonhalogenbonds, e. g., polymers and copolymers of vinyl chloride. It'is importantthat the antimony oxide and the halogen-containing thermoplasticsubstance or substances, which together are designated herein as (A),also be employed in weight ratios within the ranges hereinbeforementioned. After this second treatment the treated cellulosic materialis dried, e. g., by allowing it to stand at Mm temperature or by heatingit at an elevated temperature such, for instance, as atatemperaturewithin the range of 40 or 50 C. up to 100 or 105 C.

From the foregoing description it will be noted that the ingredients of(A) and (B) may be applied to the cellulosic material in one stage (i.e., a one-bath system) or in two stages (i. e., a twobath system); or,in other words, in the form of at least one and not more than twoaqueous liquid compositions containing the same. It is important thatthe aqueous composition containmg the ingredients of (B) have a pH offrom about 3 to about 7, more particularly a pH within the range ofabout 3 /2 or 4 to about 5 or 6, since at the lower pH values (belowabout 3) the tensile strength losses in the treated goods are excessivewhile at the higher pH values (above about 7) the treated textiles havemuch poorer fire resistance.

Regardless of the method of impregnation of the fibrous cellulosicmaterial with the aforementioned ingredients, it is important that theingredients of (A) and (B) be employed in a weight ratio of 1 part ofthe former to from 0.2 to 8 parts, e. g., from 0.5 to 6 parts, of thelatter. In all cases the total amount of the ingredients of (A) and (B)with which the cellulosic material, e. g., a cotton or viscose rayontextile material, initially is impregnated is suiiicient to impart flameresistance thereto upon heating within the range of 135 C. to 200 C. andthereafter washing to remove any residual water-soluble substances.'Thus, the total amount of the ingredients of (A) and (B) with which thecellulosic material is impregnated advantageously is such that thefinished flame-resistant textile contains from about 10% to about 50% bywe=ght (which in some cases may be as high as about 75% by weight whenthe matter of the hand of the treated material is relativelyunimportant), based on the ner similar to that described in thecopending application of Maurice R. Burnell and William J. Van Loo, Jr.,Serial No. 64,418, filed December 9, 1948, with particular reference tocompositions wherein the ingredients are of the kind and are used in theproportions set forth in our aforementioned copending application SerialNo. 64,416.

When a two-bath system of applying the ingredients is employed, thefirst bath is prepared by dissolving in water the proper proportions of(1) guanidine phosphate or other water-soluble salt of anoxygen-containing acid of phosphorus in which the phosphorus atom has avalence of 5 and (2) cyanamide, dicyandiamide or a mixture thereof. Thisbath should be within a pH range of from about 3 to about '7. The bathalso may contain a small amount, advantageously not over 7% by weight ofthe ingredients of (l) and (2), of a polyalkylene polyamine, preferablysuch a polyamine which is normally a solid or which has a boiling pointsubstantially above 200 C., e. g., triethylene tetramine, tetraethylenepentamine, hexamethylene tetramine, etc. The ingredients are dissolvedin water merely by stirring and heating at a suitable temperature, e.g., at 40 C. to 70 C. or higher. The concentration of ingredients in theaqueous bath may be varied as desired or as conditions may require, butusually they constitute from about 30% to about 50% by weight of theaqueous solution. The composition of a typical bath is as follows:

Approximate per cent by weight Monoguanidine phosphate.. 29.0 Cyanamide14.5 Hexamethylene tetramine 2.0 Water 54.5

salt of a condensation product of an aldehyde,

specifically formaldehyde, and a naphthalene sulfonic acid. Thisdispersion is passed through a colloid mill in order to reduce theparticle size to one micron. To the resulting dispersion is then added adispersion of a polyvinyl halide polymerization product, moreparticularly a polyvinyl chloride polymerization product, e. g.,polyvinyl chloride itself or a vinyl chloride copolymer comprisingmainly vinyl chloride, for instance a copolymer of, by weight, 80 to 99%of vinyl chloride (in the copolymer molecule) and 20 to 1% of vinylidenechloride, a lower alkyl acrylate (e. g., methyl, ethyl, etc., acrylates)or a vinyl ester of an aliphatic monocarboxylic acid (e. g., vinylacetate, vinyl propionate, etc.) or other thermoplastic substancecontaining at least 20% by weight of combined halogen and capable ofrupturing under heat at carbon-halogen bonds. The mixture is thoroughlyagitated until a homogeneous liquid composition or dispersion isobtained. The concentration of solids in this dispersion may be variedas desired or as conditions may require, but usually they constitutefrom about 10% to about 30% by weight thereof.

Anysuitable apparatus may be employed in applying the treatingcomposition (used in a onebath process) or compositions (used in atwo-bath process) to the cellulosic material. For example, the dry orsubstantially dry cellulosic textile to be treated may be immersed inthe aqueous composition or compositions and then passed through pressurerolls, mangles or centrifugal extractors to secure uniform impregnationand a controlled said agent is applied in one or two distinct steps orstages, is adjusted so that the finished textile captains from about 10%to about usually from 10% to 50% by weight, based on the dry weight ofthe untreated textile, of washfast impregnant. As has been indicatedhereinbefore, when the matter of hand of the finished textile isimportant, it generally contains not more than about 50%, e. g., from 10or 15% to 30 or 40%,

the textile un-- 7 based on the dry weight of the untreated textile. ofwashfast impregnant.

After impregnating the cellulosic textile with an aqueous dispersioncontaining the ingredients of both (A) and (B) or with a solutioncontaining the ingredients of (B) only, the treated material is dried toremove most or substantially all of the liquid present therein, afterwhich it is heated at a higher temperature of the order of about 135' C.to about 200' C. During this latter heat treatment a substantial loss ofsolids takes place, which may be as much as one-half to two-thirds ofthe total weight of the ingredients of (B) with which the cellulosicmaterial initially was impresnlted. Hence, inordertoobtainafinishedtextilecontaining from 10to or,inthose cases where desired, up to 85 orby weight, based on the dry weight of the untreated textile, of washfastimpregnant, the amount of solids in the textile as initially impregnatedshould be suillcient'ly high to allow for this weight loss of solidsduring the heat-treating and washing steps.

Inorderthatthoseskilledintheartbettermay understand how the prwentinvention may be carried into eii'ect, the following examples are givenby way of illustration and not by way of limitation. All'parts andpercentages are by weight.

This example illustrates the preparation and use of a single-bath or"pad liquor" in carrying the present invention into effect.

Preparation of a dispersion of antimony trioride A small amount ofdispersing agent, more particularly 13 parts of the sodium salt of acondensation product of formaldehyde and a naphthalene sulfonic acid(Tamol P) is dissolved in 57'! parts of water. Under rapid stirring witha homogenizing type of mixer, 410 parts of finely divided antimonytrioxide is added to the solution. The resulting dispersion is thenpassed through a colloid mill to reduce the average particle size to 1micron or less.

' Preparation of pad liquor A typical formula for the preparation of thepad liquor is as follows:

Park Monoguanidine phosphate 290 Cyanamide 145 Hexamethylene tetramine20 Water 31s Antimony oxide dispersion (prepared as described above) 136Aqueous dispersion containing 5546%, by

weight of an unplasticined vinyl chloride copolymer containing betweenand by weight of vinyl chloride in the copolymer 91 The monoguanidinephosphate, cyanamide and hexamethylene tetramine are added to the watermet-Dd about 20% toabout5%, e. 3., about 15% to 10%, of an alkylacrylate, more particularly a lower alkyl acrylate such, for instance,as

methyl, ethyl, propyl or butyl acrylate.

Treatment of fabrics A cellulosic fabric such, for example, as cottonclothoravlseoserayonfabricisimmersedinthe pad liquor and immediatelypassed through two rubber squeeze rolls, the presure being adjusted sothat the so-called fwet pick-up" of pad liquor bythefahrieha %hyweightofthe dry, imtreated fabric. After drying the untreated fabric, e. g., byheating at 60'-70 C., the dried fabric is heated at 100' C. for from 10to 15 minutes. Thereafter the fabric is rinsed well in water to removeresidual water-soluble substances therefrom, and again is dried (forinstance at about co -w- (2.).

Iightysqmreeottonfabrictreatedasabove dcscribedhadadryadd-onof32%byweight oi the dry, untreated fabric. The results ofverticaliiametestsofthisfahricwereasfollows: 3 inchcharlengthafter1and5washes,respectively,and0and4secondsafter-3lowafter land 5washes, respecflvely.

This example illustrates the preparation and 03: two baths in carryingour invention into Bath 1 Parts Honoguanidine phosphate 290 CyanamideHexamethylenetetramine 20 Water 545 The above-named solid ingredientsare dissolvedinthewaterbystirringandheatingat 0'-50C.Thepllofahathpreparedinthis manner-was.

Aqueous dkpersion containing 55-56% by weight of a vinyl chloridecopolymer such as described under Example 1.- 199 Finely dividedantimony trioxide 58 Dispersing agent, more particularly the sodium saltof a eondemation product of formaldehyde and naphthalene sulfonic acid(Tamol P) 2 Water 741 Treatment of fabricsThesameprocedueisfollowedintreatinga eellulosicfabricwiththeingredientsofBath 1 asisdeseribedanderlxamplel.Thedryadd-on for 80 square cotton fabric that had been thusly treatedwas 19%. The treated, rinsed and dried fabric is then immersed in Bath 2and immediately passed through rubber squeeze rolls, the pressure ofwhich is adjusted so that the wet pick-up of the dispersion by thefabric is approximately 100% by weight of the dry fabric resulting fromthe initial treatment. The wet fabric is dried at a suitabletemperature, e. g., by heating at 60-70 C. The additional dry add-on forthe aforementioned 80 square cotton fabric was 12.6%. The subsequentheat treatment that was applied to the dried fabric was the same as inExample 1. The flame resistance of the final, treated 80 square cottonfabric was as follows: Vertical flame test-2% inches and 3%, inches charlength and 1 second and 6 seconds afte.- low after 1 and washes,respectively.

The following examples are illustrative of further variations in theingredients and proportions thereof that may be used in the preparationof the treating compositions of our invention and of their use inimparting flame-resisting characteristics to cellulosic materials of thekind described in the first paragraph of this specification, moreparticularly cotton cloth, using both one-bath and two-bath processes.The procedure, in general, was as follows:

Preparation of pad liquor A. FOB ONE-BATH PROCESS A dispersion of finelydivided antimony trioxide was prepared as follows:

The dispersing agent was dissolved in the water, and the finely dividedmetallic oxide was incorporated slowly therein under high-speedstirring. After all the metallic oxide had been dispersed, thedispersion was passed through a. colloid mill (clearance: 0.002 inch).The particle size of the dispersed solid was, for the most part, onemicron or less. Aggregates having a particle size up to 3 microns may bepresent in the dispersion.

The water-soluble salt of the oxygen-containing acid of phosphorus andthe water-soluble nitrogenous substance, which ingredients are morespecifically identified in the various tables which follow, weredissolved in water, using heat if necessary to effect solution. Theabove dispersion of the finely divided antimony trioxide and adispersion of a thermally unstable thermoplastic substance containing atleast 20% of combined halogen and capable of rupturing under heat atcarbon-halogen bonds, e. g., a vinyl chloride polymerization product,more particularly a vinyl chloride copolymer of the kind described underExample 1, were then added to the solution of the other two ingredients,and the resulting mixture was thoroughly agitated to obtain asubstantially homogeneous aqueous dispersion.

B. FOR TWO-BATH PROCESS The first bath comprises an aqueous solution ofthe water-soluble nitrogenous substance (cyanamide, dicyandiamide or amixture thereof) and the water-soluble salt of the oxygen-containingacid of phosphorus. The second bath contains the dispersion of thefinely divided antimony trioxide and of the halogen-containingthermoplastic substance.

Application to fabrics A. USING ONE-BATH PBocEss Weighed strips of thecotton fabric were impregnated with the pad liquor and passed betweenrubber squeeze rolls. The pressure on the rolls was adjusted so that awet pick-up of not less than 110% was obtained; that is, the weight ofthe aqueous dispersion picked up, expressed as a percentage of theweight of the dry fabric, was not less than 110%. The treated fabricswere dried at 60-80 C. and then heated at a higher temperature in aforced-draft oven. The heated fabrics were thoroughly rinsed for 10minutes in a container into which water was running. The fabric wasdried at 60-80 C. and again weighed after allowing it to'stand for atleast one hour in free contact with the atmosphere. The per cent add-onwas determined by subtracting the initial dry weight from the final dryweight after rinsing, and dividing the difference by the initial dryweight and multiplying the quotient by 100.

B. USING TWO-BATH PROCESS The pad liquor or the first bath was appliedto the fabric in exactly the same manner as inthe one-bath process.

The pad liquor of the second bath was applied to the fabric (pretreatedas described above), using a wet pick-up of -125% and drying at 6080 C.

Washing procedure Flame tests Flame tests were made using a, speciallyconstructed apparatus and a procedure which followed in general thatgiven in ASTM Tentative Specifications Designation: D626-41T, issued1941. Samples 2 /2 inches by 10 inches were cut with the long dimensionparallel to the warp and others parallel to the fill. The apparatusconsisted of a hood, a shield around the test piece, a Bunsen burner anda holder for the sample. The fabric to be tested was suspendedvertically in the shield, which was placed in a hood with the fan off,the fabric being suspended in the shield by means of a clamp at the topand bottom. The door of the hood was then closed. The burner hadpreviously been regulated to a luminous flame 1 inches high, and wasplaced under the suspended sample so that the end of the sample extended=54 inch into the fiame. The flame was held under the sample for 12seconds and then extinguished. The duration of after-flaming of thesample was measured by means of a stop watch. And tendency of the sampleto after-glow or smoke was noted and timed if possible. The total lengthof char in inches was measured by the tear length produced with atearing weight equal to approximately 10% of the tearing strength of theunburned fabric.

The pH of the bath of pad liquor (pH of Bath 1 in the case of a two-bathprocess) as well as the pH of rinsings from the treated fabric after Inthis example the water-soluble salt of the oxygen-containing acid ofphosphorus was either monoguanidine phosphate o monosodium phosphate.The water-soluble nitrogenous substance was cyanamide, the finelydivided metallic oxide was finely divided antimony trioxide and thehalogen-containing thermoplastic substance was a vinyl chloridecopolymer such as that described under Examples 1 and 2, moreparticularly an unplasticised copolymer of, by weight, about 85% ofvinyl chloride and about of an albl acrylate. The ingredients wereapplied by a twobath process, the second bath being an aqueousdispersion containing, by weight, 5.8% of antimony trioxide and 11% ofthe aforementioned copolymer. Further information on the treatment of 80square cotton fabric and on the results I 12 square cotton fabric was129 and 125, respectively; the dry add-on of the treated fabric was 3.1and 16.1 from Baths 1 and 2, respectively. The results of the verticalfiame tests of theflltnl-I treated fabric were as follows: ff- Charlength, 3 and 3% inches and after-glow. 1 and 9 seconds after 1- and 5washes, respectively.

EXAMPLE8 In this example the water-soluble salt of the oxygen-containingacid of phosphorus was monoguanidine phosphate and the water-solublenitrogenous substance was dicyandiamide. The ingredients which are givenbelow in percentages by weight of the pad bath were applied by a onebathprocess to 80 square cotton fabric.

Ingredients: Percent by weight Water (including that introduced with theNH: as NHaOH) Remainder The pH of the pad bath was 7.2; the wet pickupof the treated fabricwas 117% and the dry obtained appear inTable I.add-on, 15.5%. Results of vertical fiame tests Table I w i m Ratio r Tm3 Percent Total PM We Used flfifii i Add'on gff gf Vertical Charred TimeAfter-Glow,

P I am in Length, Inches Sec.

Such HIPOI Bath 1 Bath 2 1 Wash 5 Washes 1 Wash 5 Washes Monoguanidlnehosphatm--. 1.0 use 1s 1s m as 4 e o 25 130.-.- p 1:7 l:4.4 l4 l8 5;: 54 21 Do 1:5 1:3. 1 l5 l6 4 6 Do 1:2 1:1.2 ll 17 3 3X Do 2:1 3.2:1 Z 186.6 7.4 4;: 4 5 2 Monoeodlum phosphate 1:1.2 1:1 16 19 4.3 5. 7 3 4 0 5EXALIPLE 4 In this example the water-soluble salt of the were 3% and 4inches char length and 1 and 5 seconds after-glowafter l and 5 washes,respectively.

EXAMPLE 7 Same as Example 2 with the exception that 145 parts ofdicyandiamide was used in place of 145 parts of cyanamide, hexamethylenetetramine was omitted from the formulation, and the material which wastreated was viscose rayon fabric weighing three and one-third ounces persquare yard. The pH of Bath 1 was 4.2. The wet pickups of Baths 1 and 2were 131 and respectively. The dry add-ons from Baths 1 and 2 were 13.1and 18.5. respectively. The treated fabric had a char length, after avertical flame test, of 3 inches and an after-glow of 5 seconds after 1appear in Table II. 60 wash.

Table II Per Cent Dry Vertical Charred Tim. After-Glow, Total Add-Onrial? pH Length, Inches Sec.

Bath mum's Bath 1 Bath 2 1 Wash owns 1 Wash 5 Washes 1s 1a 4.0 0-4 ex 4%s 5 EXAMPLE 5 10 It will be understood. of course. by those skilled Sameas Example 2 with the exception that parts of dicyandiamide was used inplace of 145 parts of cyanamide. The pH of Bath 1 was 4.6;

in the art that our invention is not limited to the particularingredients, proportions thereof and application methods described inthe above illus trative examples. As has been mentioned hereinthepercent wet pick-up of Baths 1 and 2 on 80 15 before, the water-solublenitrogenous substance 13 i may be cyanamide, dicyandiamide, or any mirture thereof, that is, mixtures of these substances in any proportions.We prefer to use cyanamide alone as the water-soluble nitrogenoussubstance.

Any water-soluble salt of an oxygen-containing acid of phosphoruswherein the phosphorus atom has a valence of 5, numerous examples ofwhich have been given earlier herein and, also, in our aforementionedcopending application maybe used, for instance:

Diguanidine polyphosphate Guanylurea phosphate Biguanide phosphatesodium dihydrogen phosphate Disodium hydrogen phosphate Dipotassiumhydrogen phosphate Ammonium polyphosphate Ethylene diamine phosphateEthylene diamine polyphosphate Primary cyclohexylamine phosphate Primarymorpholine phosphate Secondary pyridine phosphate Mixtures of such saltsmay be employed as well as salts of mixtures of such acids which includeorthophosphoric acid, metaphosphoric acid and pyrophosphoric acid, themixed acids being sometimes collectively designated as polyphosphoricacid.

The oxide of antimony, more particularly antimony in'oxide, is anessential ingredient of the treating agents used in practicing ourinvention. It may act catalytically to accelerate dehalogenation of thethermally unstable, halogen-containing thermoplastic substance and topromote more rapid hydrohalide (i. e., hydrogen halide) is resistant toflame even after numerous laundering or dry-cleaning operationa,Furthermore, by using the ingredients within the proportions statedhereinbefore, a flame-resistant textile having a good hand or feeling tothe touch and without excessive tendering (in many cases without anytendering) of the textile is obtained. As will be readily appreciated bythose skilled in the textile art, the matter of hand or feeling to thetouch is, for most applications, of considerable importance from bothsaleability and utility standpoints.

The fundamental treating compositions of this invention may be modifiedby incorporating formation at temperatures near that at which thermaldecomposition of the cellulosic material occurs.

The thermoplastic substance may be any thermoplastic material (e. g., avinyl resin, more particularly a vinyl halide polymerization product)containing at least 20%, more particularly at least 80% and preferablyat least by weight of combined halogen (e. g., chlorine, bromine, etc.)and which is capable of rupturing under heat at carbon-halogen bonds,numerous examples of which materials have been given hereinbefore.Additional examples include the halogenated diphenyls (e. g.,pentachlorodiphenyl, pentabromodiphenyl, etc.) and the halogenated (e.g., chlorinated, brominated, etc.) naphthalenes, which compounds containat least 20% by weight of combined chlorine, bromine or other halogen.We prefer to use polyvinyl chloride or a vinyl chloride copolymercontaining at least 80% by weight of combined (i. e., combined in thecopolymer molecule) vinyl chloride, more particularly a copolymer of, byweight, from about 80% to about 99% of vinyl chloride and thereinvarious modifying agents which aid in further improving theflame-resistant characteristics of the treated cellulosic material orwhich facilitate the technique of application. For instance, thecompositions may also contain minor amounts (e. g., from 1 to 30% byweight of the total solids content) of such g ow retardants as theglow-retarding borates, phosphates. Pyrophosphates, etc., e. g., zincborate, zinc phosphate, zinc ammonium phosphate, stannic phosphate,phenyl diamido phospate, melamine pyrophosphate, etc. Agents which havea buffering effect on the composition after being applied to the fabricor other textile, e. g., calcium carbonate, magnesium oxide,hexamethylene tetramine and other polyalkylene polyamines, etc., may beincorporated into the treating compositions as desired or as conditionsmay require.

The pH of the bath containing the ingredients of (B) in a two-bathprocess or the bath containing all of the ingredients in a one-bathprocess should be adjusted to a pH (glass electrode pH) within the rangeof from about 3 to about 7, e. g., a pH of from about 3 /2 or 4 to about5 or 6, if the pH of the aqueou composition containing these ingredients(water-soluble salt of the oxygen-containing acid of phosphorus andwater-soluble nitrogenous substance) is not initially within a pH rangeof from about 3 to about 7. Preferably the pH of the aqueous compositioncontaining the ingredients of (B) is between 4 and 6, e. g., about 5.

The present invention is applicable to the production of a wide varietyof flame-resistant cellulosic materials, e, g., wearing apparel of allkinds, especially children's clothes and clothing used by the armedforces, curtains, draperies, sheeting, furniture coverings, linings forelectric blankets, net fabrics, non-woven fabrics, chenilles, etc., andwhich are made of cellulosic materials such as are described in thefirst paragraph of this specification and elsewhere herein. Otherapplications of the flame-resistant products of our invention includethose described in Chapters VII and VIII of the aforementioned fromabout 20% to about 1% of an acrylic ester, 1

book, edited by Little, entitled Flameproofing Textile Fabrics.

The terms flame resistance and flame-resistant as used herein and in theappended claims with reference to cellulosic materials. specificallycellulosic textiles, are used generically to include within theirmeanings treated cellulosic materials (e. g., treated fabrics) which,after ignition, will continue to burn at a relatively slow rate as wellas those which, after ignition, will burn over only a limited areabeyond that directly exposed to the source of ignition and which may bespecifically designated as fire-resistan cellulosic materials. It willbe apparent from the examples herein given that most of the products ofour invention properly fall within the specific 15 classiflcatimi offire-resistant cellulosic materials.

The terms "textile" and "textile material as used generically herein andin the appended claims include withintheir meanings filaments, flbers,rovings, slivers, threads, yarns, twisted yarns, etc., as such or inwoven, felted or otherwise formed fabrics, sheets, cloths and the like.

We claim: I

1. The method of imparting flame resistance to a cellulosic textilematerial of the class consisting of natural celluloses, regeneratedcelluloses. and mixmres thereof, said method comprising impregnatingsaid material with an association of (1) an aqueous liquid compositionhaving a pfloffromabout3toabout'landcontaining (6) ingredients initiallyin the form of a watersoluble salt of an oxygen-containing acid ofphosphorus wherein the phosphorus atom has a valence of and awater-soluble nitrogenous substance of the group consisting ofcyanamide, dicyandiamide and mixtures thereof, said salt of anoxygen-containing acid of phosphorus and said nitrogenous substancebeing employed in a weight ratio of 1 part of the former calculatedasHsPQtoirom02to55partsofthelatter, and (2) an aqueous liquidcomposition containing (b) ingredients comprisin a finely divided oxideof antimony and a thermoplastic halogencontaining, organic substancehaving at least 20% by weight of combined halogen and capable ofrupturing under heat at carbon-halogen bonds, said finely divided oxideof antimony and said thermoplastic substance being emplwed in a weightratio of 1 part of the former to from 0.8 to 20 parts of the latter, andthe said ingredients of (a) and (b) being employed in a weight ratio of1 part of the latter to form 0.2 to 8 parts of the former; heatin thetextile material after it has been impregnated with a compositioncomprising the aqueous liquid composition of (1) at a temperature withinthe range of about 135' C. to about 200 C. and washing the resultingmaterial to remove any residual water-soluble substances therefrom, thetotal amount of the compositions of (1) and (2) with which thecellulosic material initially is impregnated being such that thefinished fiame-resistanttextlle contains from about 10% to about 75% byweight, based on the dry weight of the untreated textile, of washfastimpregnant.

2. A method as in claim 1 wherein the aqueous composition of 1) and theaqueous composition of (2) are applied simultaneously in a single bath.

3. A method as in claim 1 wherein the cellulosic textile material is acotton textile material.

4. A method as in claim 1 wherein the cellulosic textile material is aviscose rayon textile material.

5. A flame-resistant cellulosic material of the class comisting ofnatural celluloses. regenerated celluloses and mixtures thereof, saidmaterial resulting from the method of claim 1.

6. An aqueous dispersion, suitable for us in imparting flame resistanceto cellulosic textile materials selected from the group consisting ofnatural celluloses, regenerated celluloses and mixtures thereof, havinga pH of from about 3 to about 'I and comprising (1) a finely dividedoxide of antimony and (2) a thermoplastiehalogen-containing organicsubstance containing at least by weight of combined halogen and capableof rupturing under heat at carbon-halogen bonds, the ingredients of (1)and (2) which together are designated hereinafter as (A),being 18employedinaw'eightratioofl partoftheformertofrom0.6to20partsofthelatterandbeingdispersed in water containingingredients initially in the form of (3) a water-soluble salt of anoxygencontaining acid of phosphorus wherein the phosphorus atom has avalence of 5 and (4) a watersoluble nitrogenous substance of the groupconsisting of cyanamide, dicyandiamide and mixtures thereof, theingredients of (3) and (4) which together are designated hereinafter as(B), being employed in a weight ratio of 1 part of the former calculatedas HsPOi to from 0.2 to 5.5 parts of the latter, and the ingredients of(A) and (B) being employed in a weight ratio of 1 part of the former tofrom 0.2 to 8 parts of the latter.

'1. An aqueous dispersion as in claim 8 wherein the finely divided oxideof antimony is antimony trioxide, the thermoplastic halogen-containingorganic substance is a vinyl chloride polymerization product, thewater-soluble salt or an oxygenccntaining acid of phosphorus ismonoguanidine phosphate and the water-soluble nitrogenous substance iscyanamide.

8. A method of imparting flame resistance to a textile materialcomprising fibers of a cellulosic material of the class consisting ofnatural celluloses, regenerated celluloses, and mixtures thereof, saidmethod comprising impregnating saidtextile material with the compositionof claim 6, drying the impregnated material, heating the dried materialat a temperature within the range of 135 C. to 200 C. and washing theresulting mata'ial to remove any residual water-soluble substancestherefrom, the total amount or said ingredients of (A) and (B) withwhich the cellulosic textile material initially is impregnated beingsuch that the finished flame-resistant textile contains from about 10%to about 50% by weight,

based on the dry weight of the untreated textile, of washfastimpregnant.

9. A method of imparting flame resistance to a textile comprising fibersof a cellulosic material of the class consisting of natural celluloses,regenerated celluloses and mixtures thereof, said method comprisingimpregnating said textile with an aqueous dispersion having a pH of fromabout 3 to about 7 and comprising (1) a finely divided antimony trioxideand (2) a thermoplastic vinyl chloride polymerization product containingat least 40% by weight of combined chlorine, the ingredients of (1) and(2), which together are designated hereinafter as (A), being employed ina weight ratio of 1 part of the former to from 0.6 to 20 parts of thelatter and being dispersed in water containing ingredients initially inthe form of (3) a water-soluble guanidine phosphate and (4) cyanamide,the ingredients of (3) and (4), which together are designatedhereinafter as (B), being employed in a weight ratio of 1 part of theformer calculated as HJPO to from 0.3 to 4.5 parts of the latter, andthe ingredients of (A) and (B) being employed in a weight ratio of 1part of the former to from 0.2 to 8 parts of the latter. drying theimpregnated material, heating the dried material at a temperature withinthe range or 135 C. to 200 C., and washing the resulting material toremove any residual watersoluble substances therefrom, the total amountof the ingredients of (A) and (B) with which the cellulosic textilematerial initially is impr gnated being such that the finishedflame-resistant textile contains from about 10% to about by weight,based on the dry weight of the untreated textile, of washfastimp'regnant.

10. A method as in claim 9 wherein the water- 17 soluble guanidinephosphate of (3) is monoguanidine phosphate.

11. A method as in claim 9 wherein the aqueous dispersion also containsa small amount, not exceeding about 7% by weight of the ingredients of(B), of a polyalkylene polyamine having a boiling point substantiallyabove 200 C.

12. A flame-resistant textile material of the class consisting ofnatural celluloses, regenerated celluloses and mixtures thereof, andwhich results from the method of claim 9.

13. A method of imparting flame resistance to a textile comprisingfibers of a cellulosic material of the class consisting of naturalcelluloses, regenerated celluloses and mixtures thereof, said methodcomprising impregnating said textile with an aqueous solution having apH within the range of from about 3 to about 7 and containingingredients initially in the form of (1) a watersoluble salt of anoxygen-containing acid of phosphorus wherein the phosphorus atom has avalence of 5 and (2) a water-soluble nitrogenous substance of the groupconsisting of cyanamide, dicyandiamide and mixtures thereof, theingreclients of (1) and (2), which together are designated hereinafteras (B), being employed in a weight ratio of 1 part of the formercalculated as H3PC-i to form 0.2 to 5.5 parts of the latter; heating theimpregnated textile at a temperature within the range of 135 C. to 2000.; washing flle of this patent:

0.6 to 20 parts of the latter, the ingredients of (A) and (B) beingemployed in a weight ratio of 1 part of the former to from 0.2 to 8parts of the latter and the total amount of the ingredients of (A) and(B) with which the said textile is impregnated being such that thefinished flameresistant textile contains from about 10% to about 75% byweight, based on the dry Weight of the untreated textile, of washfastimpregnant.

14. A flame-resistant cellulosic textile material of the classconsisting of natural celluloses, regenerated celluloses and mixturesthereof, and which results from the method of claim 13.

15. A method as in claim 13 wherein the watersoluble salt of anoxygen-containing acid of phosphorus is a guanidine phosphate, thewatersoluble nitrogenous substance is cyanamide, the finely dividedoxide of antimony is antimony trioxide and the thermoplastichalogen-containing substance is a vinyl resin containing at least 40% byweight of combined chlorine.

16. A method as in claim 15 wherein the textile is a, cotton fabricmaterial.

17. A method as in claim 15 wherein the watersoluble guanidine phosphateis monoguanidine phosphate.

ANNE MACNIILLAN LOUKOMSKY. ROY H. KIENLE. THEODORE F. COOKE.

REFERENCES CITED The following references are of record in the UNITEDSTATES PATENTS Number Name Date 2,178,625 Clayton et al Nov. 7, 19392,286,308 Rosser June 16, 1942 2,413,163 Bacon Dec. 24, 1946 2,427,997White Sept. 23, 1947 Certificate of Correction Patent No. 2,520,103August 22, 1950 ANNE MACMILLAN LOUKOMSKY ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows:

Column 1, line 20, for the word use read us; column 10 line 66, for Andread Any; column 14, line 25, for phospate read phosphate; column 15,line 38, and column 17 line 28, for form read from; and that the saidLetters Patent should be read as corrected above, so that the same mayconform to the record of the case in the Patent Oflice. Signed andsealed this 2nd day of January, A. D. 1951.

THOMAS F. MURPHY,

Assistant Uommz'ssz'oner of Patents.

1. THE METHOD OF IMPARTING FLAME RESISTANCE TO A CELLULOSIC TEXTILEMATERIAL OF THE CLASS CONSISTING OF NATURAL CELLULOSES, REGENERATEDCELLULOSES AND MIXTURES THEREOF, SAID METHOD COMPRISING IMPREGNATINGSAID MATERIAL WITH AN ASSOCIATION OF (1) AN AQUEOUS LIQUID COMPOSITIONHAVING A PH OF FROM ABOUT 3 TO ABOUT 7 AND CONTAINING (A) INGREDIENTSINITIALLY IN THE FORM OF A WATERSOLUBLE SALT OF AN OXYGEN-CONTAININGACID OF PHOSPHORUS WHEREIN THE PHOSPHORUS ATOM HAS A VALENCE OF 5 AND AWATER-SOLUBLE NITROGENOUS SUBSTANCE OF THE GROUP CONSISTING OFCYANAMIDE, DICYANDIAMIDE AND MIXTURES THEREOF, SAID SALT OF ANOXYGEN-CONTAINING ACID OF PHOSPHORUS AND SAID NITROGENOUS SUBSTANCEBEING EMPLOYED IN A WEIGHT RATIO OF 1 PART OF THE FORMER CALCULATED ASH3PO4 TO FROM 0.2 TO 5.5 PARTS OF THE LATTER, AND (2) AN AQUEOUS LIQUIDCOMPOSITION CONTAINING (B) INGREDIENTS COMPRISING A FINELY DIVIDED OXIDEOF ANTIMONY AND A THERMOPLASTIC HALOGENCONTAINING, ORGANIC SUBSTANCEHAVING AT LEAST 20% BY WEIGHT OF COMBINED HALOGEN AND CAPABLE OFRUPTURING UNDER HEAT AT CARBON-HALOGEN BONDS, SAID FINELY DIVIDED OXIDEOF ANTIMONY AND SAID THERMOPLASTIC SUBSTANCE BEING EMPLOYED IN A WEIGHTRATIO OF 1 PART OF THE FORMER TO FROM 0.6 TO 20 PARTS OF THE LATTER, ANDTHE SAID INGREDIENTS OF (A) AND (B) BEING EMPLOYED IN A WEIGHT RATIO OF1 PART OF THE LATTER TO FORM 0.2 TO 8 PARTS OF THE FORMER; HEATING THETEXTILE MATERIAL AFTER IT HAS BEEN IMPREGNATED WITH A COMPOSITIONCOMPRISING THE AQUEOUS LIQUID COMPOSITION OF (1) AT A TEMPERATURE WITHINTHE RANGE OF ABOUT 135*C. TO ABOUT 200*C.; AND WASHING THE RESULTINGMATERIAL TO REMOVE ANY RESIDUAL WATER-SOLUBLE SUBSTANCES THEREFROM, THETOTAL AMOUNT OF THE COMPOSITIONS OF (1) AND (2) WITH WHICH THECELLULOSIC MATERIAL INITIALLY IS IMPREGNANTED BEING SUCH THAT THEFINISHED FLAME-RESISTANT TEXTILE CONTAINS FROM ABOUT 10% TO ABOUT 75% BYWEIGHT, BASED ON THE DRY WEIGHT OF THE UNTREATED TEXTILE, OF WASHFASTIMPREGNANT.